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thc blood breath levels

According to Beard Bros Pharms, a recent study has found that THC levels in breath and blood tests do not associate with impairment. This is a finding that confirms studies that have previously researched on the same subject and came to same conclusions. Even with these new findings confirming that breath and blood samples cannot be used to show impairment, many states are continuing to stand behind their cannabis restrictions. Let’s hope lawmakers themselves catch up on the science behind cannabis quickly.

All about the study

Throughout the study, THC levels in the breath and blood of cannabis consumers were taken before and after they smoked. These levels and the duration of the participants’ impairment after inhalation cannabis were measured by the researchers. The majority of patients had residual THC levels in their blood (at levels of 5 ng/ml or above). Meaning, that despite the signs of any imparement, THC was detected in these patients’ blood. This shows the evidence of THC in breath or blood is not an accurate method for determining cannabis impairment.

Next, the scientists discovered an opposite link between THC blood levels and disabling performance after cannabis inhalation. They noted how their findings show that single measurements of specific delta-9-THC blood concentrations do not correspond with impairment. Futhermore, these findings show that using the “legal limitations” for delta-9-THC cannot be justified scientifically.

“The authors of the study also discovered the presence of THC in the patients’ breath at baseline, despite the absence of any indicators of impairment. “Our findings are consistent with those of others who have shown that delta-9-THC can be identified in breath up to several days after last usage,” they concluded. Because the dominant methods for breath-based testing for recent cannabis use rely only on the detection of delta-9-THC, false-positive test results could occur if delta-9-THC is detected in breath outside of the impairment window” ( Beard Bros Pharms).


Here in the United States, there are numerous states who have implemented specific limits to establish cannabis impairment. Usually, this limit is 5 ng/ml of THC, which makes it illegal to drive a vehicle with blood THC concentrations exceeding said limit. As we know, THC can stay in our systems for long periods of time post consumption depending on the users method of choice. Therefore, these limits that are put into place are often criticized for their ability to imply that drivers who display above the legal levels of THC in breath and/or blood but are actually not impaired.


Regardless of the findings discussed in this specific study and alongside other studies that show similar outcomes, one thing still remains. States across the United States will continue to implement laws surrounding THC breath and blood levels and impariment. Roughly, about twelve states a zero-tolerance when it comes to cannabis and operating a vehicle. It looks like time will tell where legal limitations and cannabis impairment are headed. Will science be enough?

All in all, here is to hoping that the science of cannabis continues to come forward and the stigma surrounding cannabis changes for the better.

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